Dam it!
“Rivers know this: there is no hurry. We shall get there some day.”
Above is A. A Milne’s famous quote, one that is often bandied about by Instagram life coaches or blasted across naff posters outside University lecture halls. But what people don’t realise is that this saying is no longer true. See, of all humanity’s great achievements: from inventing the wheel to Nandos hot sauce, creating large dams is right up there with the worst things we’ve ever done. Once heralded as a new dawn for ‘green’ energy, dams and their affiliated hydropower stations have transformed the rivers that they are installed on; and have totally destroyed the ecological and cultural systems that had depended on the river.
Now I’ve promised myself to keep this blog piece succinct and will do my best to not stray too far into the weeds, but when you’ve had an academic background in freshwater and seen the damage dams can do it’ll be hard to keep this under 2000 words. Have no fear though. This will not be a scientific paper and there is no test, but I feel quite strongly people should know more about the issues facing freshwater ecosystems, and in doing so know how they can help.
So where do we begin, or better yet when do we begin? See, rivers and the ecosystems they support can take millions of years to evolve in response to the natural earth process around us; such as the local climate and tectonic movements to name but a few. It is important to think of a river as a constantly moving and evolving creature, not some constrained beast that we sadly see today in England. A river needs space to move to respond to changes in its catchment and adapt accordingly. Changes to flow, such as a flooding event, can lead to meanders being formed, or ox bow lakes being born where these meanders become so narrow they effectively pinch off from the main channel. The way a river responds to events and finds its natural equilibrium will create a complex mosaic of habitats: ponds, ox bow lakes, pools and rapids, which creates more niche’s (basically a role for specific creatures in the environment….see it as a 9-5 job for a given organism) and greater biodiversity.
Animals respond to the uniqueness of each river and over time some species may like it so much they reside there permanently and develop behavioural or physical attributes to make life in the river as easy as possible. This is called adaptation, which given enough adapting can cause speciation, and what was once one species has now become two.
Still with me? This is where I bring in a cool fact to wake you up….
Despite available freshwater (lakes and rivers) taking up less than 3% of the world’s surface area, there are more species of fish in freshwater environments than there are marine. Given that the marine area accounts for well over 55% of the worlds surface area this fact is pretty mind-blowing. However, this heterogeneity (nice word for uniqueness and diversity) of freshwater ecosystems can sadly play against it when we meddling humans interfere.
We’ve covered that changes in a river happen naturally, so what’s the big concern with dams then? Alterations to natural systems occur over a long period of time, and are usually either non-permanent or are surmountable changes that the river can adapt to e.g. a flooding event. The creation of a dam is usually concluded over a period of a few years, which compared to the millennia in which it takes a river to find equilibrium, and an ecosystem to flourish alongside, is literally the blink of an eye. Moreover, the creation of a dam makes a permanent alteration to the river with flow (crucial for moving river), sediment (critical for river bed structure and the delta downstream) and temperature (key for thermal optimum of organisms which have adapted to the river) all being completely flipped on its head.
The changes brought about by dams mean that the species we spoke about earlier – who loved a particular river so much they decided to adapt to it – often find themselves in an ecosystem that now no longer supports their niche (9-5 job); at least in the immediate area of the dam but quite often large stretches of the river. These dams don’t respect habitats, and quite often fragment populations of organisms apart, leading to local extinctions (known as extirpation) if new areas to inhabit are not found, and a lower genetic diversity in the species as the population has just been cut in half.
Importantly to sturgeon (had to bring them in at some point didn’t I!) and this expedition, dams are effectively permanent barriers to the migration of some species. Many animals rely on free passage through rivers (and estuaries and the sea) to complete their life cycles. Most people are familiar with salmon and the huge feats demanded of them to spawn. Well the same is true for many species of sturgeon, and their close relatives, with the Chinese paddlefish (now extinct in the wild…) and Chinese sturgeon previously migrating over 3000km up the Yangtze to spawn.
Migratory species, such as the sturgeon, have perfected their spawning specificity over millennia. Only spawning on certain gravels, at certain times of the year and under certain flow conditions. As reader will now hopefully grasp, all of this become redundant once a dam goes up. It is no surprise that one of the most dammed major rivers on earth bore witness to the first extinction of a sturgeon species; with the Chinese sturgeon a rather large canary in the coal mine for freshwater ecosystems globally.
Setting off on this expedition I really thought I would be seeing exceptional rivers, in natural conditions with human interference at a low …. at least for some sections. This makes me seem like an optimist in life (jury’s out on that one) but I have been speechless at times so far with how shocking some rivers have been treated and yet overwhelmed by the hard work being done to protect what is left and reverse some of the declines.
From rivers dried out in northern Italy, a river segmented by dams in the Tarn Gorges to a constrained Danube; across Europe we have had a real go at hitting rivers hard. However there is still hope. Species reliant on freshwater ecosystems which only a few decades ago seem destined for extinction, are making come back – the beaver is a good example of this – greater enforcement and environmental protection is being written into law across the EU and community action groups have never been heard louder.
I will continue to do my part to help reverse the decline and I would urge you, the reader, to join me.
What can we do
1. Oppose large projects that will impact aquatic systems, and scrutinise the environmental impact report that needs to be produced before any development begins.
2. Ensure the free flowing rivers that remain are not impacted by dams – there’s a big battle going on in Albania on the Vjosa river, the last great undammed river in Europe…. Go check out how you can help.
3. Limit your water use. Rivers so often play second fiddle to agriculture and urban needs, with this stress likely to be furthered with the onset of severe climate change. I’m not suggesting not washing, but try a shower instead of a bath. Those fortunate enough to have a garden, install tanks that will capture rainwater instead of using the tap.
4. Volunteer in your local Wildlife Trust or river community group and join in the task of protecting arguably the most diverse ecosystem type on the planet (sorry coral reefs).
5. Lastly, go out and enjoy the wonders of being on a river. Swim (caution, read below), canoe, chill. If your local river or lake does not look fit for swimming then demand the local authorities and water companies to do something about it. Write, complain, shout!
Britain has a terrible history with its rivers and lakes, and we are still dragging our heels even in the 21st century. To give you sense of how lost we are, in 2019 an environmental watchdog found that pollutants in English rivers were now so high that no river in the country is consistently safe for swimmers. ZERO!
However, somehow we still have some incredible biodiversity in rivers in the UK. Their survival after hundreds of years of being treated with neglect inspires me. The Thames, declared ecologically dead in the 1950s now has populations of migratory fish, seals and eels calling it home. Reversals can be made given the political will and public demand of people. If right now is the UK at a low, imagine what our rivers and lakes could look like after a generation of care!
Don’t sit on your hands and expect, good things come to those that persevere not wait.
